64 Mr. H. N. Moseley on the [Nov. 25, 



leadiug to it from the circle of the tentacles. Suspended in this reticu- 

 late tissue are the testes, large sacs filled with spermatic cells disposed 

 sometimes in one, sometimes in two vertical rows ; they occupy the 

 interior of the ampullae. These corals are dioecious. Cryptohelia resembles 

 Stylaster most closely in structure, and is also dioecious. 



Vegetable Parasites. — The corallum of both Millepora and Pocillopora 

 is permeated by fine ramified canals, formed by parasitic vegetable organ- 

 isms of the same nature as those described by Dr. Carpenter and Professor 

 Kolliker as occurring in the shells of mollusks &c. The organisms 

 were found in abundant fructification ; they are green, but otherwise 

 appear to be fungi, as are the parasites of shells &c. Similar parasites 

 are to be found in various coralla from widely distant parts of the world. 



Conclusions. 



Heliopora is most undoubtedly an Alcyonarian. The number of its 

 mesenteries, and the distribution with regard to them of the retractor 

 muscles, the form and number of its tentacles, are 'decisive evidence in 

 the matter ; and this evidence is borne out by almost every item of histo- 

 logical structure. In the peculiar manner in which the retraction of the 

 tentacles takes place, viz. by introversion, Heliopora seems to differ from 

 all other Alcyonarians except Corallium*. From both Corallium and 

 Tubipora, Heliopora differs in that the hard tissue of its corallum shows 

 no signs of being composed of fused spicules, but in its histological struc- 

 ture most closely resembles Zoantharian Corals. With the Milleporidae 

 and with the Pocilloporidae and Seriatoporidae Heliopora is allied solely 

 on account of its possession of tabulae. Now that an Alcyonarian is 

 added to the list of various Anthozoa possessing these peculiar structures, 

 their presence becomes of less classifactory importance even than Professor 

 Verrill proved it to be. There can hardly be a doubt that Seriatopora 

 will prove to be, like Pocillopora, a Zoantharian ; and Millepora is certainly 

 very different in structure from Heliopora. Heliopora thus stands quite 

 alone amongst modern forms ; and in the peculiar structure of its cellular 

 ccenenchym it is so remarkable that it is unlikely that on examination of 

 the soft parts of other corals, at present known from their coralla only, 

 any near relatives of it will be discovered. Amongst extinct forms, how- 

 ever, Heliopora has several close allies, and the genus itself existed in the 

 Cretaceous period. The genus Polytremacis differs apparently only in the 

 more perfect development of the so-called septa, which reach to the 

 centres of the tabulae. The genus occurs in the Chalk, Greensand, and 

 in Eocene formations. Heliopora has, further, a very closely allied palaeo- 

 zoic representative in Heliolites, in which the ccenenchymal tubes are pro- 

 vided with very closely placed tabulae. 



* I have found no information on this point in any of the text-books; but in 

 Schmarda's ' Zoologie ' there is a figure of Corallium, copied from Lacaze-Duthiers's 'Hist. 

 Nat. du Corail,' in which the tentacles are drawn introverted as they are in Heliopora. 



